Reinforced flexible hose

ABSTRACT

A reinforced flexible hose comprising as least a first inner extruded tubular layer and at least a second extruded tubular layer with a tubular reinforcement fabric provided between said first and second hoses. The two tubes are joined so as to form a homogeneous unit by their mutual contact surfaces, by gluing or molecular adhesion, for example. The end portion of the hose increases in width so much as to make it possible to achieve a better mechanical hold with the standard junctions to which it is bound to be fixed. The thickness increases at the end portions may either be constant along its whole length, or start gradually toward the end.

FIELD OF THE INVENTION

The present invention relates to a reinforced flexible hose,particularly but not exclusively suitable for the field of gardening.

BACKGROUND OF THE INVENTION

Flexible hoses are known which belong to the cheap category of themarket. In order to control production costs, these are produced joiningtwo coaxial tubular layers having reduced thickness, by means of theinsertion of a knitted or woven reinforcement therebetween.

The above mentioned types of hoses are usually employed in connectionwith mounts, joints or irrigation tools having standard size andmanufactured on a mass scale. Tubes having a reduced thickness are hardto join to the standard quick-fit joints, therefore a short while afterthe hose starts being used, water leaks are often found to occur throughthe joining area.

A further disadvantage of said known hoses is that they are prone to beeasily twisted and damaged where they connect with the joint, most oftenin proximity of the water mains tap.

Several attempts to overcome the above shortcomings were made in thepast, for instance fixing joints that are pressed and made to besuitable for the hose either at the production stage or resorting tohose joints to be fixed between the hose and the standard joint, saidhose joints being made of a similar material to that the tube is made ofand further being suitably secured.

Although on the one hand the above solutions lead to a reinforcement ofthe hose wall, thus making its bending more difficult, on the other handthey bring about an increase in production costs, that makes them nottoo favourably welcomed by the users of this specific market.

A further disadvantage is that in case the hose breaks and is subject toshortening at its end portions, it turns out to be mandatory to usestandard joints that have the known sealing problems deriving torn thedifficulty there is to find special joints distributed by the normallarge-scale retail trade.

In case reinforcements are made by hose joints, it is likewise difficultto find spare hose joints to replace those that cannot be recoveredafter a damaged hose has been shortened.

EP-A-0 118 613 discloses a flexible hose for shower and sanitaryfixtures having all the features mentioned in the preamble of theattached claim 1. However, the thickness of one of the inner and outerlayers is increased gradually and in a linear way and is not constantalong the whole extension of longitudinal end portions. Thus, the endportion with increased thickness must have a relatively long extensionin order to provide a sufficient resistance for the joints.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a new type ofhose that is capable of being easily and effectively joined to thestandard joints, in so doing maintaining its enhanced sealing propertiesand avoiding water leaks, while retaining its cost effectiveness at theproduction stage and remaining comprised in the low-cost category on themarket.

A further specific object of the present invention is to design a hoseof the type outlined above that features a structure that is capable ofminimising the risks of breakage, twisting or detachment at the joiningwith the tap or with the watering tool.

The above objects are accomplished by providing a reinforced flexiblehose that comprises in accordance with the attached claim 1 ischaracterised in that the increased thickness is substantially constantalong the whole extension of the longitudinal portions and in that thethickness increase is non-linear towards the free end of saidlongitudinal portions.

Thank to said reinforcements, it is thus possible to use joints of thestandard type, maintaining a mechanical connection at the reinforced endof the hose, preventing the hose to detach from the joint and reducingthe danger of twisting the end portion thereof during handling by theuser.

A further object of the present invention is to provide a simple methodfor the production of a hose according to the present invention, thatallows the production of great quantities thereof on a continuous basisat low costs, by using the existing equipment, though suitably modifiedfor that purpose.

The above object is accomplished by providing a method for theproduction of a reinforced flexible hose that in accordance with theattached claim 9 comprises the following steps:

-   -   a) extruding at least one first inner tubular layer (2) made of        plastic material having a substantially constant advancement        speed (V);    -   b) weaving a textile fabrics material (4) onto the outer surface        of said first layer (3), at the same advancement speed (V);    -   c) extruding at least one second tubular layer (2) made of        plastic material at substantially the same advancement speed (V)        of said first layer (2) and said tubular reinforcement (4) so as        to allow a homogeneous fitting of said layers (2, 3) and form a        wall having a predetermined thickness (S);    -   d) providing longitudinal portions (A, B) having an increased        thickness (S′, S″) in said first and/or second tubular layer        (2,3) so as to enhance resistance of the hose in order to favour        a stable mating to hose end joints or to other irrigation        accessories;    -   e) cutting the hose in correspondence of said longitudinal        portions (A,B) having increased thickness,        -   characterised in that said increased thickness is made            substantially constant along the whole extension (A) of said            longitudinal portions and with non-linear increase towards            the free end of said longitudinal portions,

Step d) can be accomplished by varying the advancement speed of at leastone of the said layers in correspondence at said longitudinal portionsthereof having greater thickness. The speed change can be accomplishedinstantaneously, then the speed is kept at a constant value for aportion of its length.

As an alternative, step d) can also be accomplished by varying the flowof the extruded material having increased thickness.

The finished hose alternatively features end-longitudinal portionshaving increased thickness and being frusto-conically shaped as withtheir larger side in common, or it may otherwise feature a cylindricallyshaped thicker portion.

At the end of the process, the hose is cut in correspondence of thesection having maximum diameter or of the middle area of the portionhaving increased thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will be moreclearly apparent in the light of the following description of apreferred but not exclusive embodiment, given by way of not limitingexample, of a reinforced flexible hose illustrated in the attacheddrawings, wherein:

FIG. 1 shows a longitudinal section view of the hose of the prior art,

FIG. 2 is a cross-sectional view of the hose shown in FIG. 1;

FIG. 3 is a general perspective view of an embodiment of the reinforcedflexible hose according to the present invention;

FIG. 4 is a longitudinal sectional view of a first embodiment of thepresent invention;

FIG. 5 is a general perspective view of a second embodiment of thereinforced flexible hose according to the present invention;

FIG. 6 is a cross sectional view of the embodiment of flexible hoseshown in FIG. 5;

FIG. 7 is a cross sectional view of the hose shown in FIG. 6;

FIG. 8 is a schematic side view of a device for the production of a hoseaccording to the present invention, with said device in a firstoperating position;

FIG. 9 is a schematic side view of the device shown in FIG. 8, with saiddevice in a second operating phase.

DESCRIPTION OF SOME PREFERRED FORMS OF EMBODIMENT

With reference to FIGS. 1 and 2 a flexible hose of the prior art isshown, generally indicated with the reference numeral 1, that isessentially formed by two tubular coaxial layers, respectively an innerlayer having an inner diameter Di and an outer layer having an outerdiameter De, and with a tubular reinforcement or stock 4 made of fibrousmaterial, of the woven or knitted type, that is interposed between thetwo layers 2, 3 and extends over the entire length thereof.

Layers 2, 3 are made of extruded plastic materials and are mutuallyjoined in correspondence of their mutual contact surface with theinterposition of reinforcement 4 so as to form a wall having an overallthickness S that is substantially constant, except the workingtolerances connected with the extrusion of layers with the weaving ofthe reinforcement fabrics 4.

FIGS. 3 and 4 show a first embodiment of hose 1 according to the presentinvention, said hose having a thickness S′ along a portion A of itslength starting at one end 5, said thickness being increased withrespect to thickness S of the portion of hose 1 that is the furthestfrom its end 5.

In this first embodiment, tube wall 1 has either a substantiallyconstant thickness along the whole portion A past circular step 6 or anextremely short conical connecting portion. Thus it will be possible topromote a stable watertight mating with connecting organs or gardeninghose joints, thereby avoiding water leakages and any sort of breakagesat those hose joints.

According to a second embodiment of the reinforced flexible hose of thepresent invention, illustrated by FIGS. 4, 5 and 6, the increase inthickness of the hose wall is accomplished by a gradual increase inthickness of the outer layer 3 starting from point 6 where the wall hasa thickness that is equal to the average is normal thickness S.Therefore thickness increases in a linear fashion until it reaches amaximum value S″ in correspondence of end 5. This is accomplished bymeans of an increase in thickness limited to the outer layer 3.

In general, longitudinal portions A and B having increased thicknessallow the accomplishment of a stable mechanical grip with standardjoints or irrigation tools and accessories of the threaded ferrule type,that has an enhanced mechanical and hydraulic resistance where the hosehas a greater thickness.

In view of the fact that the greatest stresses caused by the user'shandling are localised where the joints are coupled to the hose, thereinforcement according to the present invention brings about areduction in the ease with which the hose bends and twists, with afurther advantage for the user.

Layers 2, 3 that form the hose can be made of the same or of differentmaterials, in accordance with the technical and aesthetic requirementsto be met. The inner tubular layer can for instance be made of amaterial that is suitable for allowing contact with food or beverageproducts without releasing dangerous or harmful particles, whereas theouter layer can be made of a less noble material that is very unsuitablefor alimentary use.

It is also possible td envisage further outer layers or films made ofmaterials with anti-abrasive properties, or likewise being shieldingagainst ultraviolet (UV) radiation, that have purely ornamental andaesthetic, with various different uniform or patterned colourings andpigmentations.

According to the present invention, reinforcement 4 can also be laidover exclusively one extruded tubular layer rather than being interposedbetween two co-extruded layers, if and whenever appropriate.

Furthermore it is possible to form the increased thickness exclusivelyon the inner tubular layer 2, as well as it is possible to provide theincreased thickness of both layers in correspondence of the same area.

In FIGS. 8 and 9 a machine for the production of a plastic hoseextrusion according to the present invention is schematically depicted,that is part of a full production line for the flexible hose.

In FIG. 8 an intermediate product is shown and indicated with thereference numeral 11 said product consisting of the inner tubular layer2, whereon the woven or knitted tubular reinforcement fabric 4 isformed.

The semi-finished product 1′ is guided by rollers 7, 8, 9 up to anextrusion head 10 that forms the outer tubular layer 3 coaxially to theproduct 1′. For a first embodiment, the flow Q of the material extrudedfrom head 10 is constant and the thickness of the extruded tubular layer3 deposited around product 1′ depends on its advancement speed V withinhead 10. Advancement speed V of finished tube 1 is generally constant atthe very end of the production process, therefore a decrease ΔV in thespeed is accomplished combining the actuation of roller groups 7, 8 and9 and 11, 12, 13 accompanying the hose. In particular, moving downwardsthe roller 8 located upstream of the extrusion head 10 and movingupwards the roller 12 located downstream of the extrusion head 10, untilpositioning them as shown in FIG. 9, the length of the path the tubemust move along is varied, thereby reducing its velocity from V to V−ΔVin correspondence with head 10.

A change in speed ΔV can then be accomplished either gradually orinstantaneously, depending on the configuration the portion withincreased thickness must have. Applying a suitable algorithm to thechange in advancement speed, end portions with an increased thicknesscan be shaped is differently.

In a second embodiment of the production method according to the presentinvention, it is possible to accomplish an increase in thickness by avariation ΔQ of extruded material flow Q, deposited by the extrusionhead 10.

Downstream of the extrusion head 10 there may also be provided acontainer 14 wherein the finished hose 1 that is still warm can besubjected to further working process, or be simply allowed to cool down.

The production of the hose is carried out on a continuous basis and thelength of the end portions where the increased thickness of the hosewall are formed is defined as a function of the overall length of thehose to be produced. When the production of a first batch is over, thesegments of hose are severed at the middle point of their thickenedportion. In order to identify the point where the tube is to be cut, thepigmentation and colouring of the outer layer of the finished hose maybe varied. Such pigmentation and colour May be varied along the endportions in order to produce hoses having longitudinal portions with adifferent colour, so as to easily highlight the area where variations inthickness occur. To this end, it is likewise possible to carry out theinjection of pigmented material having different colours through head10.

The overall colouring of the hose, that is of its outer layer, andpossibly as well as of the woven reinforcement fabrics can beaccomplished with materials that are either uniformly coloured or thatare striped, using the same or different colours. Colour combinationsare also possible in so doing obtaining a wide range of aesthetic,optical and visual effects.

1. Multiple layer reinforced flexible hose comprising at least one innertubular first layer made of extruded plastic material, at least oneouter tubular second layer made of extruded plastic material, a tubularreinforcement made of a textile material interposed between said firstand said second layer, said first and said second layer extending oversubstantially the entire length of said tubular reinforcement and beinghomogeneously joined in correspondence of their mutual contact surfaceso as to define a wall having an overall predetermined thickness, an endportion of said wall having an increased thickness along a longitudinalportion of predetermined extension to thereby provide watertight sealingaction with external connection organs, wherein said increased thicknessis substantially constant along the whole extension of each saidlongitudinal portion and a non-linear, stepped increase with respect tothe rest of the hose, said end portion with said increased thicknesshaving a substantially constant outer diameter and a smooth andcontinuous outer surface without discontinuities over an entire lengthof said end portion, said stepped increase being of substantiallycircular shape.
 2. Reinforced flexible hose according to claim 1 whereinsaid stepped increase has a substantially short conical shape. 3.Reinforced flexible hose according to claim 1 wherein said increasedthickness is only localized on said outer tubular layer.
 4. Reinforcedflexible hose according to claim 1 wherein said increased thickness isonly localized on said inner tubular layer.
 5. Reinforced flexible hoseaccording to claim 1 wherein said increased thickness is localized onboth said outer tubular second layer and said inner tubular first layer.6. Reinforced flexible hose according to claim 1 wherein at least one ofsaid first and said second layer is colored with different pigmentationsalong different parts of its length to provide longitudinal portions ofsaid layers with different colors.
 7. Reinforced flexible hose accordingto claim 6 wherein said second layer is provided with a change ofcoloring and pigmentation in correspondence of the stepped thicknessincrease to identify where the hose is to be cut.
 8. Reinforced flexiblehose according to claim 1 wherein said hose comprises one or morefurther inner, outer or middle tubular layers, made of plastic material,having technical and/or aesthetic functions.
 9. Reinforced flexible hoseaccording to claim 8 wherein said one or more further plastic materiallayers are chosen from the group comprising food compatible,anti-abrasives, UV shielding and ornamental films.